1. Field of the Invention
This invention relates to a film rewinding device and particularly to a rewinding operation when the film parts from a take-up spool.
2. Description of the Prior Art
When a film contained in a film magazine, such as a 35 mm still camera film, is used for photographing, the film, which has been rewound to the inside of a film magazine upon completion of photographing, must be again pulled out for processing by a developing machine. At that time, the film can be readily pulled out if the tip of the film remains outside the magazine. However, if the film has been completely rewound without leaving the film end outside the magazine, it must be taken out by breaking the magazine or by using a special tool.
In the case of a 35 mm camera, such troubles may be avoided by rewinding the film by hand after completion of photographing, and by feeling a change in the torque of a rewinding shaft to stop the rewinding operation before the film is completely rewound to the inside of a film magazine. However, in cases where such film rewinding is accomplished with an electric driving device means for automatically stopping such film rewinding by detecting the completion of rewinding is necessary. In the conventional electric film driving device, means for mechanically detecting the presence or absence of film on a take-up spool is disposed inside the camera. With such means provided, the operation of a rewinding motor disposed on the side of the electric driving device is stopped in response to a signal of the mechanical detecting means. The stopping arrangement of this type necessitates the provision of the mechanical detecting means on the side of the camera. This complicates the structure of the camera while the simplification of the structure is desired for making the camera compact and light in weight. On the other hand, such detecting means are unnecessary for camera operators who are using no electric driving device in combination with the camera. For such people, an increase in the price of a camera due to such unnecessary detecting means is hardly acceptable.
It is therefore an object of this invention to provide a film rewinding device which automatically stops the film rewinding operation with detecting means disposed in the rewinding device for detecting the variation of the film rewinding load of a rewinding mechanism.
It is another object of this invention to provide an electric circuit which applies a braking action to a rewinding motor when the film rewinding operation is to be automatically stopped.